CakePHPをインストールしようとしたら、以下のようなエラーメッセージが出ます。

前提・実現したいこと

Cakephpをインストールを試みてます。
macOS Catalina バージョン10.15.7
Vagrant (2.2.10)
Virtualbox6.1
Vagrantbox centos/7 2004.01
PHP 7.2.34

最後にcakePHPをGoogle Chromeで192.168.33.10/sampleと開こうとしたら、以下のようなエラーメッセージが出ました

発生している問題・エラーメッセージ

エラーメッセージ
Warning: require(/var/www/html/sample/vendor/autoload.php): failed to open stream: No such file or directory in /var/www/html/sample/webroot/index.php on line 31

Fatal error: require(): Failed opening required '/var/www/html/sample/vendor/autoload.php' (include_path='.:/usr/share/pear:/usr/share/php') in /var/www/html/sample/webroot/index.php on line 31

試したこと

自分なりに調べて、composer dumpautoload とcomposer install というがあったので、ターミナルで記入したら、
Composer could not find a composer.json file in /var/www/html
To initialize a project, please create a composer.json file as described in the https://getcomposer.org/ "Getting Started" section
というメッセージがでました。

フォルダにsampleにcomposer.jsonのファイルが入ってます。以下が中身です。

{
    "name": "cakephp/app",
    "description": "CakePHP skeleton app",
    "homepage": "https://cakephp.org",
    "type": "project",
    "license": "MIT",
    "require": {
        "php": ">=7.2",
        "cakephp/cakephp": "~4.1.0",
        "cakephp/migrations": "^3.0",
        "cakephp/plugin-installer": "^1.3",
        "mobiledetect/mobiledetectlib": "^2.8"
    },
    "require-dev": {
        "cakephp/bake": "^2.0.3",
        "cakephp/cakephp-codesniffer": "~4.2.0",
        "cakephp/debug_kit": "^4.1",
        "josegonzalez/dotenv": "^3.2",
        "phpunit/phpunit": "~8.5.0",
        "psy/psysh": "@stable"
    },
    "suggest": {
        "markstory/asset_compress": "An asset compression plugin which provides file concatenation and a flexible filter system for preprocessing and minification.",
        "dereuromark/cakephp-ide-helper": "After baking your code, this keeps your annotations in sync with the code evolving from there on for maximum IDE and PHPStan/Psalm compatibility.",
        "phpstan/phpstan": "PHPStan focuses on finding errors in your code without actually running it. It catches whole classes of bugs even before you write tests for the code."
    },
    "autoload": {
        "psr-4": {
            "App\": "src/"
        }
    },
    "autoload-dev": {
        "psr-4": {
            "App\Test\": "tests/",
            "Cake\Test\": "vendor/cakephp/cakephp/tests/"
        }
    },
    "scripts": {
        "post-install-cmd": "App\Console\Installer::postInstall",
        "post-create-project-cmd": "App\Console\Installer::postInstall",
        "check": [
            "@test",
            "@cs-check"
        ],
        "cs-check": "phpcs --colors -p  src/ tests/",
        "cs-fix": "phpcbf --colors -p src/ tests/",
        "stan": "phpstan analyse src/",
        "test": "phpunit --colors=always"
    },
    "prefer-stable": true,
    "config": {
        "sort-packages": true
    }
}

これも調べましたが、解決策が見つかりませんでした。